on top/below the reaction arrow

[DrMattOglesby]

okay so i forgot; the things on top of the reaction arrow in a chemical reaction, are other reactants correct? and the things on bottom are the solvent or physical properties like heat, right?
and all reactions follow this rule?

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[Chemist0157]

That's how I've always seen it. Also, if the stuff above/below is numbered, it is understood that these "extras" are added in steps.

 

[DrMattOglesby]

okay--one more for ya:

in what form does the carboxylate anion exist?

i learned the carboxylic acid (-COOH) will donate a proton to become more stable because it will have a resonance structure.
But in the back of my mind I am thinking about delocalized electrons as well.

Aren't delocalized electrons and resonance structures different?

 

[tco]

okay--one more for ya:

in what form does the carboxylate anion exist?

i learned the carboxylic acid (-COOH) will donate a proton to become more stable because it will have a resonance structure.
But in the back of my mind I am thinking about delocalized electrons as well.

Aren't delocalized electrons and resonance structures different?

In pH above about 4, the carboxylic acid molecule will exist as an anion. It's not donating the proton because it will become more stable, it's donating the proton because COO(-) is such a stable anion and can survive without that proton much easier than the other bases in solution.

Resonance structures are our way of showing delocalized electrons. There's no way to draw on paper where an electron is, but we do the best we can do. Resonance structures show the hybrid structures of all contributing molecules. For example, although it's a minor resonance structure contributor, chlorine can "form" a double bond to stablilize a charge.

Hope that helps.

 

[spo01]

Aren't delocalized electrons and resonance structures different?

I had that exact same problem arise on my Organic test and my teacher marked me wrong. But we're really playing with semantics here and we both looked in a few books to find this answer. I put down on a test question that a negative charge on Iodine is more stable than a negative charge on Chlorine because it was more "delocalized". What I simply meant was that the charge was spread out over the atom, but because I put 'delocalized' he took off because that is a word that is used only when speaking of resonance.

 

[tco]

Meh...That's pretty extreme. The fact that I is larger than Cl makes it a more stable ion, you're completely correct. Delocalized is generally a term used with molecules...That's a bit harsh to take points off when he obviously knew the direction that you were going with it.